Upgrade SEP 11 to 12, then migrate to new server

How to upgrade SEP 11 to SEP 12 and then migrate to new server,

Dear Forum,

Can anyone please give me a step by step about how to upgrade and migrate of SEP 11 to SEP 12, we have a customer who request instalation above. History :

1. Current antivirus : SEP 11
2. Total user : 600 user
3. Need to upgrade to SEP 12 + add more 300 user when upgrade to SEP 12, totaly 900 user
4. After all upgrade, then migrate the SEPM to a new server.

Regards

R,